276 
NATURE 
[Aug. 4, 1870 
other phenomena suggest that the zodiacal light is a disc of bodies 
or vapours travelling around the sun; yet others suggest that the 
zodiacal light is a phenomenon of our own atmosphere. But the 
only theory which accounts at once for a// observed phenomena, 
is that which regards the zodiacal light as simply due to the 
continual presence in the sun’s neighbourhood of bodies or va- 
pours (meteoric or cometic, or both) which come there from 
very far beyond the earth’s orbit, and pass away again on their 
eccentric orbits. A disc thus formed of continually varying con- 
stituents would shift in position, and would wax and wane in 
extent as well as splendour, precisely as the zodiacal light is ob- 
served to do. RICHARD A, PRocTror 
Spontaneous Generation 
THE physical capacity of fungus-spores to throw out my- 
celium, and from that to be able to reproduce a parent (or, ac- 
cording to Dr. Bastian, to produce a fungus de nove), shows a 
complicated organisation greatly above that of the monad. 
From a careful examination of Dr, Bastian’s experiments and 
figures, I am led to believe that the majority of the ovoid bodies 
referred by him to fungus-spores are nothing of the kind, and 
that if they really belong to the vegetable kingdom atall, they are 
perfect unicellular plants in themselves reproducing their kind 
by subdivision ; the presumed mzyce/ium 1 should refer to the 
bursting of the cell-walls, and consequent discharge of the con- 
tents; a by no means uncommon occurrence with unicellular or- 
ganisms. It is, however, tmpossible to follow the author in his 
speculaticns regarding these Lodies, as his measurements are so 
imperfect, and in several instances, where most wanted, omitted 
altogether. A few of the bodies certainly bear an external ap- 
pearance to fungus-spores (for instance C, Fig. 11, which might 
be referred to Russela or Scleroderma), but as no size is given it 
is impossib!e to form an opinion, Perhaps Dr. Bastian will say 
on what data he refers such objects as are shown on Fig, 3, to 
fungns-spores, and by what characters he knows the mycchal 
filaments to be such: the ‘ half-grown” spore (?) described on 
page 197 has most extraordinary characters for such an object; 
for, says the author, ‘the nuclear particle within was seen 
moving from end to end of the cell.” 
Had not Dr. Bastian distinctly affirmed that the spores were 
generated at once from heterogenous materials, I should have 
assumed his belief in the presence of the perfect plants in the 
infusions, though the detached spores were all he met with in 
his experiments ; for ifany organism originates independently of a 
parent similar to itself, surely it is reasonable to expect the pro- 
duction to be at once perfect, and not in the egg state. Could 
an oviparous animal be produced from heterogenous materials, 
surely one would net expect eggs first to appear. In referring 
these unicellular bodies to spores, Dr. Bastian appears to me to 
have defeated the very object he had in view. 
That some of the bodies figured are dona fide spores of fungi 
seems very probable, and that they were produced by ordiuary 
parents, seems equally so, for the slight neck-like elongaiioa or 
spot, which is analogous with the placental scar in animals and 
flc wering plants, is clearly p.esent in the ower right-hand object 
(Fig. 11) and the lower left-hand object (Fig. 13). Ifthese things 
were evolyed without parents, surely nature would not have 
given them an umbilicus; it is far more reasonable to suppose 
that true spores got into the infusions (and perhaps germinated) 
by some accident similar to the three recorded instances where 
foreign budies were undoubtedly found. (Note, p. 197.) 
It seems to me rational enough to suppose that unicellular 
bodies and objects of the lowest possible organisation may be 
heterogenously produced from the inorganic world, for here the 
line between one and the other is so fine as scarcely, if at all, to 
be perceived ; indeed, the Brownian motion of monads, some 
spermatozoids, and the particles forming many inorganic in- 
fusions, are scarcely, if at all, to be distinguished from each other. 
From moneds and unicellular organisms, however, spore-pro- 
ducing fungi are greatly removed, and the economy, functions, 
and structure of most of the latter are now so well known, that 
it would be simply impossible to convince any botanist that a 
spore like C (Fig. £1) could be produced from any other quarter 
than the hymenium of a well-defined parent. 
I cannot see that the production of motile zoospores in Achlya 
(p. 174) has any bearing on the subject, as here we have an 
already “ving parent; and motile zoospores are by no means 
uncommon in the vegetable kingdom ; their movements, how- 
_ the liquid does not ; the former is consequently liberated. 
ever, so far as I have been able to observe them, do not differ 
from the Brownian movements seen in the inorganic world. 
It is clear that no definite conclusions can be arrived at regard- 
ing these bodies and their production till a series ef accurate 
figures is published to an zzi/orm scale (with an indication of the 
colour of the cells, &c.), enlarged at least 2,000 diameters, for 
even then a monad would be no larger than a pin’s-head. It 
will then be possible to compare the bodies with actual fungus- 
spores and other bodies well known to botanis‘s and zoologists. 
Prof. Wanklyn appears to be unable to estimate the number of 
germs of fungi known to exist in the atmosphere. That ‘‘ there 
must be very many of them” is apparent from the calculation 
that, if each spore of one species only of one of the higher fungi 
germinated and reproduced its parent, the children would, in 
the first generation and in the course of a very few days, form 
a carpet all over the earth, Now, as fungi abound everywhere 
in myriads, and tue family is almost illimitable, the number of 
diffused germs is evidently beyond all calculation ; their size, too, 
is often so small that twenty could be conveniently accommo- 
dated on the diameter of a single human blood corpuscle. That 
they are alive is proved by the readiness with which, under 
favourable conditions, they may be made to germinate. It must 
also be admitted, in Prof. Wanklyn’s favour, that ‘‘they must 
weigh something,” though I am not aware of any attempt in 
that direction at present. Some of their ‘remarkably smal)” 
comporent parts are, however, made manifest by chemical re- 
action. WORTHINGTON G. SMITH 
Mildmay Park, London 
Super-Saturation 
Tue following experiments may be found interesting from 
their bearing on the latest theories advanced on the subjects of 
super-saturation and the so-called inactive state of bodies. Pro- 
fessor Tomlinson’s theory is that a super-saturated solution 
adheres as a whole to a chemically clean surface, but that a dif- 
ferential adhesion takes place in presence of a chemically unclean 
surface, because the salt or gas adheres to such a surface while 
The 
presence or absence of grease is then stated to constitute chemical 
uncleanness or cleanness. If a greasy surface can be rendered 
inactive, it is clear that both these propositions cannot be true ; 
either grease is not of itself a cause of uncleanness, or unclean 
surfaces are not necessarily active ones. The following experi- 
ments prove that the fats may be rendered inactive by the same 
processes which are applied to rods of glass or metal. 
1..A bit of composite candle was melted with a very little 
alcohol ; a glass rod was dipped in, allowed to cool, passed 
through flame ofa Bunsen’s burner, and a drop of melted fat 
deposited on surface of supersaturated solution of zincic sulphate. 
The fat solidified without affecting the solution even on prolonged 
agitation. A crystal of the salt caused instant solidification. 
2. Some solution boiled remained supersaturated for a 
fortnight with a crust of fat on the top. : 
3. Ordinary tallow treated as No. t. Inactive in solution of 
sodic sulphate solution ; touched with finger, crystallised at once. 
4. Lard cleaned simply by melting on rod passed through 
flame, allowed to cool, stirred in sulution of sodic sulphate. 
Inactive. Other end of rod active at once. 
5. Same solution boiled ; cooled, stirred with rod, treated as 
the last, and left exposed to the air for r5 minutes. Did not 
crystallise. This experiment is interesting, as showing that 
greasy substances are not specially liable to be made active by 
exposure to ordinary air. 
6. Some tallow was melted in a test-tube withcut precautions 
of any kind, and while melted was poured to the depth of half 
an inch on to solutions of ferrous, cupric, and sodic sulphates. 
In each case it was inactive. ‘Ihis is conclusive on the point in 
question. 
Theoretical objections have been. urged against the definition 
of chemical uncleanness, and I think this might now be sur- 
rendered. 
Professor Tomlinson may very likely be right in looking 
to adhesion for an explanation of these phenomena; at all 
events, far greater probability seems to attach to this view than 
to that put forth by M. Gernez, adopted by Jamin, and eyen, I 
believe, favourably noticed by the Academy itself; which is 
that only a crystal of the same salt can induce crystallisation. 
This latter view is open to the theoretical. objection tliat it 
necessitates our believing that all salts capable of supersaturation 
